[ttml2] Computed active time of <p> with multiple <span> children in relation to showBackground="whenActive"

michlord has just created a new issue for https://github.com/w3c/ttml2:

== Computed active time of <p> with multiple <span> children in relation to showBackground="whenActive" ==
Hello. I have a region with `tts:showBackground="whenActive"`
and content:
```html
<tt:div begin="00:00:00.000" end="00:00:10.000">
 <tt:p xml:id="subtitle1" region="bottom" style="paragraphAlign">
  <tt:span style="textWhite" begin="00:00:00.000" end="00:00:01.000">first</tt:span>
  <tt:span style="textWhite" begin="00:00:03.000" end="00:00:04.000">second</tt:span>
 </tt:p>
</tt:div>
```
There is a one-second gap between `first` and `second`. What is the active duration of the `<p>` element? Should I see the background between 00:00:01 and 00:00:03? My guess is that I should.

I can't find anything about this in the ttml2 specification.
I also tried looking at siml3 and it seems like I should be looking at the `endsync` attribute which is `all` by default. From this I conclude that active duration of `<p>` should be defined by a minimum of begin attributes and maximum of end attributes of the span elements.

Is this correct?

Please view or discuss this issue at https://github.com/w3c/ttml2/issues/499 using your GitHub account

Received on Tuesday, 28 November 2017 14:22:26 UTC